Phase I/II Study of Weekly Oraxol for the Second-Line Treatment of Patients With Metastatic or Recurrent Gastric Cancer

A phase Ib study of Oraxol (oral paclitaxel and encequidar) in patients with advanced malignancies

PURPOSE

Oraxol is an oral formulation of paclitaxel administered with a novel, minimally absorbed P-glycoprotein inhibitor encequidar (HM30181A). This phase Ib study was conducted to determine the maximum-tolerated dose (MTD) of Oraxol administered at a fixed dose for up to 5 consecutive days in patients with advanced malignancies.

METHODS

Part 1 of this study utilized a 3 + 3 dose-escalation design to determine the MTD of oral paclitaxel 270 mg plus oral encequidar 15 mg administered daily. Dose escalation was achieved by increasing the number of consecutive dosing days per week (from 2 to 5 days per week). Dosing occurred for 3 consecutive weeks out of a 4-week cycle. Part 2 treated additional patients at the MTD to determine tolerability and recommended phase II dose (RP2D). Adverse events, tumor responses, and pharmacokinetic profiles were assessed.

RESULTS

A total of 34 patients (n = 24 in Part 1, n = 10 in Part 2) received treatment. The MTD of Oraxol was determined to be 270 mg daily × 5 days per week per protocol definition and this was declared the RP2D. The most common treatment-related adverse events were fatigue, neutropenia, and nausea/vomiting. Hypersensitivity-type reactions were not observed. Of the 28 patients evaluable for response, 2 (7.1%) achieved partial response and 18 (64.3%) achieved stable disease. Pharmacokinetic analysis showed rapid absorption of paclitaxel when administered orally following encequidar. Paclitaxel daily exposure was comparable following 2-5 days dose levels.

CONCLUSION

The oral administration of encequidar with paclitaxel was safe, achieved clinically relevant paclitaxel levels, and showed evidence of anti-tumor activity.

Anti-tumor pharmacology of natural products targeting mitosis

Cancer has been an insurmountable problem in the history of medical science. The uncontrollable proliferation of cancer cells is one of cancer’s main characteristics, which is closely associated with abnormal mitosis. Targeting mitosis is an effective method for cancer treatment. This review summarizes several natural products with anti-tumor effects related to mitosis, focusing on targeting microtubulin, inducing DNA damage, and modulating mitosis-associated kinases. Furthermore, the main disadvantages of several typical compounds, including drug resistance, toxicity to non-tumor tissues, and poor aqueous solubility and pharmacokinetic properties, are also discussed, together with strategies to address them. Improved understanding of cancer cell mitosis and natural products may pave the way to drug development for the treatment of cancer.

Strategies and Mechanism in Reversing Intestinal Drug Efflux in Oral Drug Delivery

Efflux transporters distributed at the apical side of human intestinal epithelial cells actively transport drugs from the enterocytes to the intestinal lumen, which could lead to extremely poor absorption of drugs by oral administration. Typical intestinal efflux transporters involved in oral drug absorption process mainly include P-glycoprotein (P-gp), multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP). Drug efflux is one of the most important factors resulting in poor absorption of oral drugs. Caco-2 monolayer and everted gut sac are sued to accurately measure drug efflux in vitro. To reverse intestinal drug efflux and improve absorption of oral drugs, a great deal of functional amphiphilic excipients and inhibitors with the function of suppressing efflux transporters activity are generalized in this review. In addition, different strategies of reducing intestinal drugs efflux such as silencing transporters and the application of excipients and inhibitors are introduced. Ultimately, various nano-formulations of improving oral drug absorption by inhibiting intestinal drug efflux are discussed. In conclusion, this review has significant reference for overcoming intestinal drug efflux and improving oral drug absorption.

Probing the new strategy for the oral formulations of taxanes: changing the method with the situation

The first-generation taxanes (including paclitaxel and docetaxel) are widely used for the treatment of various cancers in clinical settings. In the past decade, a series of new-generation taxanes have been developed which are effective in the inhibition of tumor resistance. However, intravenous (i.v.) infusion is still the only route of administration, and may result in serious adverse reactions with respect to the utilization of Cremophor EL or Tween-80 as solvent. Besides, the dosing schedule is also limited. Therefore, oral administration of taxanes is urgently needed to avoid the adverse reactionss and increase dosing frequency. In this review, we first outlined the discovery and development of taxane-based anticancer agents. Furthermore, we summarized the research progress on the oral formulations of taxanes and proposed some thoughts on the future development of oral taxane formulations.

Toward a Personalized Therapy in Soft-Tissue Sarcomas: State of the Art and Future Directions

Soft-tissue sarcomas are rare tumors characterized by pathogenetic, morphological, and clinical intrinsic variability. Median survival of patients with advanced tumors are usually chemo- and radio-resistant, and standard treatments yield low response rates and poor survival results. The identification of defined genomic alterations in sarcoma could represent the premise for targeted treatments. Summarizing, soft-tissue sarcomas can be differentiated into histotypes with reciprocal chromosomal translocations, with defined oncogenic mutations and complex karyotypes. If the latter are improbably approached with targeted treatments, many suggest that innovative therapies interfering with the identified fusion oncoproteins and altered pathways could be potentially resolutive. In most cases, the characteristic genetic signature is discouragingly defined as "undruggable", which poses a challenge for the development of novel pharmacological approaches. In this review, a summary of genomic alterations recognized in most common soft-tissue sarcoma is reported together with current and future therapeutic opportunities.

Oral paclitaxel with encequidar compared to intravenous paclitaxel in patients with advanced cancer: A randomised crossover pharmacokinetic study

AIMS

Paclitaxel is a widely used anti-neoplastic agent but has low oral bioavailability due to gut extrusion by P-glycoprotein (P-gp). Oral paclitaxel could be more convenient, less resource intensive, and more tolerable than intravenous administration. Encequidar (HM30181A) is a novel, minimally absorbed gut-specific P-gp inhibitor. We tested whether administration of oral paclitaxel with encequidar (oPac+E) achieved comparable AUC to intravenous paclitaxel (IVP) 80 mg/m² .

METHODS

We conducted a multi-centre randomised crossover study with two treatment periods. Patients (pts) with advanced cancer received either oral paclitaxel 615 mg/m² divided over 3 days and encequidar 15 mg orally 1 hour prior, followed by IVP 80 mg/m² , or the reverse sequence. PK blood samples were taken up to Day 9 for oPac+E and Day 5 for IVP.

RESULTS

Forty-two patients were enrolled; 35 completed both treatment periods. AUC_0-∞ was 5033.5 ± 1401.1 ng.h/mL for oPac+E and 5595.9 ± 1264.1 ng.h/mL with IVP. The geometric mean ratio (GMR) for AUC was 89.50% (90% CI 83.89-95.50). Mean absolute bioavailability of oPac+E was 12% (CV% = 23%). PK parameters did not change meaningfully after 4 weeks administration of oPac+E in an extension study. G3 treatment-emergent adverse events occurred in seven (18%) pts with oPac+E and two (5%) with IVP. Seventy-five per cent of patients preferred oPac+E over IVP.

CONCLUSIONS

GMR for AUC was within the predefined acceptable range of 80-125% for demonstrating equivalence. oPac+E is tolerable and there is no evidence of P-gp induction with repeat administration. With further study, oPac+E could be an alternative to IVP.

Emerging nanotaxanes for cancer therapy

The clinical application of taxane (including paclitaxel, docetaxel, and cabazitaxel)-based formulations is significantly impeded by their off-target distribution, unsatisfactory release, and acquired resistance/metastasis. Recent decades have witnessed a dramatic progress in the development of high-efficiency, low-toxicity nanotaxanes via the use of novel biomaterials and nanoparticulate drug delivery systems (nano-DDSs). Thus, in this review, the achievements of nanotaxanes-targeted delivery and stimuli-responsive nano-DDSs-in preclinical or clinical trials have been outlined. Then, emerging nanotherapeutics against tumor resistance and metastasis have been overviewed, with a particular emphasis on synergistic therapy strategies (e.g., combination with surgery, chemotherapy, radiotherapy, biotherapy, immunotherapy, gas therapy, phototherapy, and multitherapy). Finally, the latest oral nanotaxanes have been briefly discussed.

Dihydro-β-agarofuran-Type Sesquiterpenoids from the Seeds of Celastrus virens and Their Multidrug Resistance Reversal Activity against the KB/VCR Cell Line

Twenty-nine dihydro-β-agarofuran-type sesquiterpenoids, including 17 new and 12 known compounds, were obtained from the seeds of Celastrus virens. The structures of the new isolates were characterized by spectroscopic methods and X-ray diffraction analysis. Among these, 20 sesquiterpenoids were evaluated for their multidrug resistance (MDR) reversal activity against the KB/VCR cell line. As a result, compounds 6 and 8 were found to exhibit MDR-reversal activity of more than 10-fold at a concentration of 2 μM, and the reversal fold (RF) ratios of compounds 19, 21, and 24 were >97.9 at a 20 μM nontoxic concentration level.

Current Perspectives on Taxanes: Focus on Their Bioactivity, Delivery and Combination Therapy

Taxanes, mainly paclitaxel and docetaxel, the microtubule stabilizers, have been well known for being the first-line therapy for breast cancer for more than the last thirty years. Moreover, they have been also used for the treatment of ovarian, hormone-refractory prostate, head and neck, and non-small cell lung carcinomas. Even though paclitaxel and docetaxel significantly enhance the overall survival rate of cancer patients, there are some limitations of their use, such as very poor water solubility and the occurrence of severe side effects. However, this is what pushes the research on these microtubule-stabilizing agents further and yields novel taxane derivatives with significantly improved properties. Therefore, this review article brings recent advances reported in taxane research mainly in the last two years. We focused especially on recent methods of taxane isolation, their mechanism of action, development of their novel derivatives, formulations, and improved tumor-targeted drug delivery. Since cancer cell chemoresistance can be an unsurpassable hurdle in taxane administration, a significant part of this review article has been also devoted to combination therapy of taxanes in cancer treatment. Last but not least, we summarize ongoing clinical trials on these compounds and bring a perspective of advancements in this field.

Discovery of Encequidar, First-in-Class Intestine Specific P-glycoprotein Inhibitor

Many chemotherapeutics, such as paclitaxel, are administered intravenously as they suffer from poor oral bioavailability, partly because of efflux mechanism of P-glycoprotein in the intestinal epithelium. To date, no drug has been approved by the U.S. Food and Drug Administration (FDA) that selectively blocks this efflux pump. We sought to identify a compound that selectively inhibits P-glycoprotein in the gastrointestinal mucosa with poor oral bioavailability, thus eliminating the issues such as bone marrow toxicity associated with systemic inhibition of P-glycoprotein. Here, we describe the discovery of highly potent, selective, and poorly orally bioavailable P-glycoprotein inhibitor 14 (encequidar). Clinically, encequidar was found to be well tolerated and minimally absorbed; and importantly, it enabled the oral delivery of paclitaxel.

The intravenous to oral switch of taxanes: strategies and current clinical developments

The taxanes paclitaxel, docetaxel and cabazitaxel are important anticancer agents that are widely used as intravenous treatment for several solid tumor types. Switching from intravenous to oral treatment can be more convenient for patients, improve cost-effectiveness and reduce the demands of chemotherapy treatment on hospital care. However, oral treatment with taxanes is challenging because of pharmaceutical and pharmacological factors that lead to low oral bioavailability. This review summarizes the current clinical developments in oral taxane treatment. Intravenous parent drugs, strategies in the oral switch, individual agents in clinical trials, challenges and further perspectives on treatment with oral taxanes are subsequently discussed.

Overcoming negatively charged tissue barriers: Drug delivery using cationic peptides and proteins

Negatively charged tissues are ubiquitous in the human body and are associated with a number of common diseases yet remain an outstanding challenge for targeted drug delivery. While the anionic proteoglycans are critical for tissue structure and function, they make tissue matrix dense, conferring a high negative fixed charge density (FCD) that makes drug penetration through the tissue deep zones and drug delivery to resident cells extremely challenging. The high negative FCD of these tissues is now being utilized by taking advantage of electrostatic interactions to create positively charged multi-stage delivery methods that can sequentially penetrate through the full thickness of tissues, create a drug depot and target cells. After decades of work on attempting delivery using strong binding interactions, significant advances have recently been made using weak and reversible electrostatic interactions, a characteristic now considered essential to drug penetration and retention in negatively charged tissues. Here we discuss these advances using examples of negatively charged tissues (cartilage, meniscus, tendons and ligaments, nucleus pulposus, vitreous of eye, mucin, skin), and delve into how each of their structures, tissue matrix compositions and high negative FCDs create barriers to drug entry and explore how charge interactions are being used to overcome these barriers. We review work on tissue targeting cationic peptide and protein-based drug delivery, compare and contrast drug delivery designs, and also present examples of technologies that are entering clinical trials. We also present strategies on further enhancing drug retention within diseased tissues of lower FCD by using synergistic effects of short-range binding interactions like hydrophobic and H-bonds that stabilize long-range charge interactions. As electrostatic interactions are incorporated into design of drug delivery materials and used as a strategy to create properties that are reversible, tunable and dynamic, bio-electroceuticals are becoming an exciting new direction of research and clinical work.

Effect of HM30181 mesylate salt-loaded microcapsules on the oral absorption of paclitaxel as a novel P-glycoprotein inhibitor

The purpose of this study was to develop HM30181 mesylate salt (HM30181M)-loaded microcapsules as a novel P-glycoprotein inhibitor for enhancing the oral absorption of paclitaxel. The effect of various carriers including hydrophilic polymers and solvents on the solubility of HM30181M were evaluated. Among the hydrophilic polymers and solvents tested, HPMC and methylene chloride (and ethanol) provided the highest HM30181M solubility. Numerous HM30181M-loaded microcapsules were prepared with HPMC, silicon dioxide and acidifying agents using a spray-drying technique, and their solubility, dissolution and physicochemical properties were evaluated. Furthermore, a pharmacokinetic study was performed after oral administration of paclitaxel alone, simultaneously with HM30181M powder or HM30181M-loaded microcapsules to rats. Among the acidifying agents investigated, phosphoric acid provided the best improvement in the solubility and dissolution of HM30181M. Moreover, the microcapsule composed of HM30181M, HPMC, silicon dioxide and phosphoric acid at a weight ratio of 3:6:3:2 remarkably enhanced the solubility and dissolution of HM30181M compared with the HM30181M powder alone. The microcapsules were spherical in shape, had a reduced particle size of about 7μm, and contained HM30181M in an amorphous state. Furthermore, this microcapsule significantly enhanced HM30181M absorption, making it about 1.7-fold faster and 1.6-fold greater after simultaneous administration, leading to about 70- and 2-fold improved oral bioavailability of paclitaxel compared with paclitaxel alone and the simultaneous administration with HM30181M powder, respectively. Thus, this novel microcapsule could be a potential candidate for effective P-glycoprotein inhibition during oral administration of paclitaxel.